The present invention relates to a seatback bar structure of a vehicle, and particularly to the seatback bar structure of the vehicle having a vehicle body provided with side panels constituting right-and-left vehicle-body side walls and a floor panel arranged between the right-and-left side panels, interconnecting the side panels, and forming a vehicle floor face, comprising a cross bar extending in a vehicle width direction above the floor panel, a leg portion connecting the cross bar and the floor panel, a guard bar fixed to an upper portion of the cross bar and made from aluminum or aluminum alloy by extrusion molding, and a link bracket, one end of which is fixed to the side panel and the other end of which is connected to the cross bar.
In general, a recent open car has an inverse-U shaped guard bar arranged in back of a vehicle seat to protect a passenger's head portion in a vehicle's rollover. This inverse-U shaped guard bar has the function to transmit a load generated in the vehicle's rollover to a floor panel so as to retrain its own deformation through efficient transmission of the load, so that a survival space of the passenger can be secured properly. Further, the open car adopts a seatback bar structure to transmit a load generated in a vehicle's side collision in a vehicle width direction because it has no roof, particularly no roof reinforcement.
Herein, the seatback bar structure is a general term for a united structure comprising a cross bar which is arranged in back of the vehicle seat and extends in the vehicle width direction, interconnecting right-and-left side panels above the floor panel, a leg portion which connects a lower portion of the cross bar and the floor panel, and a guard bar which is fixed to an upper portion of the cross bar. It can be considered that any of the cross bar, the leg portion and the guard bar (at least the guard bar among them) is made from aluminum or aluminum alloy to achieve further light-weighting of the vehicle.
In this case, it may be considered that the aluminum-made or aluminum-alloy-made guard bar is formed in the inverse-U shape by bending forming after extrusion molding, and both end portions, in the vehicle width direction, of the U-shaped guard bar are configured to pass through and fixed to penetration holes formed at the cross bar. However, this structure has a problem in that the manufacturing accuracy of the guard bar may deteriorate because the bending forming is applied to the guard bar after the extrusion molding, so that it may be difficult to attach the guard bar to the penetration holes of the cross bar.
Japanese Patent Laid-Open Publication No. H5-58240 discloses a seatback bar structure in which a pair of symmetrical and inverse-U shaped guard bars are provided at an upper portion of a cross bar. This guard bar is made by bending a steel pipe and therefore it may not be appropriate in achieving light weighting of the vehicle. Herein, it is considered that the guard bar is made from aluminum or aluminum alloy by extrusion molding or bending forming. However, in this case, there is a problem in attaching as described above.